The present invention generally relates to a safety device for racks that are vertically adjustable while controlled by an overhead rotating shaft. More specifically, the invention is directed toward a clover mechanism mounted on a rotary shaft to be used with an unbalanced free-fall dog that precludes rotation of the rotating shaft upon excessive acceleration, such as after catastrophic failure of the control mechanism for the rotating shaft.
Typically, overhead racks are used in commercial settings to conserve space within the facility. A typical rack is approximately fifty feet long (sixteen meters) and can be raised and lowered by a double chain motor that is attached to a rotating shaft. A flexible strap may wrap around the rotating shaft thereby shortening the amount of strap hanging below the rotating shaft and raising the rack. As an example, a bicycle rack consists of numerous hooks extending therefrom to hold bicycles from their front or rear wheels. The rack is raised and lowered as needed to load, view or remove the bicycles from the rack.
When a chain or belt breaks or dislodges from the gear or rotating cylinder, the rack can come crashing down. There are presently safety mechanisms to be used in association with the gear or rotating cylinder, such as the double chain in case one chain breaks or dislodges. Also, with a long rotating shaft constantly being placed under excessive stress, the shaft may fail in rare occasions.
A need exists to provide additional safety features for racks attached to rotating shafts and the like. The utilization of a construction that locks upon rapid or uncontrolled rotation of the rotating shaft is a desirable complementary safety feature.
Accordingly, it would be desirable to provide a safety lock device that is activated by rapid force on an arm of an unbalanced free-fall dog that pivotally reacts and locks before the rack drops a significant distance.
In connection with the foregoing objectives, it would also be a goal to have a safety device that allows the rack to freely move up and down at a slow rotative speed relative to the rotating shaft.
Moreover, it would be significant in the industry to provide a safety mechanism that can be attached to the rotating shaft at a location away from the chain, gears or other driven mechanisms.
It has therefore been found beneficial to produce an unbalanced free-fall dog that functions in conjunction with a clover mechanism that is mounted on the rotating shaft. Further aspects and benefits of the invention will be appreciated by those practicing the operation of rotating shafts.